xref: /openbmc/qemu/target/i386/tcg/sysemu/bpt_helper.c (revision 50a92d9b) 
1 /*
2  *  i386 breakpoint helpers - sysemu code
3  *
4  *  Copyright (c) 2003 Fabrice Bellard
5  *
6  * This library is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * This library is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18  */
19 
20 #include "qemu/osdep.h"
21 #include "cpu.h"
22 #include "exec/exec-all.h"
23 #include "exec/helper-proto.h"
24 #include "tcg/helper-tcg.h"
25 
26 
27 static inline bool hw_local_breakpoint_enabled(unsigned long dr7, int index)
28 {
29     return (dr7 >> (index * 2)) & 1;
30 }
31 
32 static inline bool hw_global_breakpoint_enabled(unsigned long dr7, int index)
33 {
34     return (dr7 >> (index * 2)) & 2;
35 
36 }
37 static inline bool hw_breakpoint_enabled(unsigned long dr7, int index)
38 {
39     return hw_global_breakpoint_enabled(dr7, index) ||
40            hw_local_breakpoint_enabled(dr7, index);
41 }
42 
43 static inline int hw_breakpoint_type(unsigned long dr7, int index)
44 {
45     return (dr7 >> (DR7_TYPE_SHIFT + (index * 4))) & 3;
46 }
47 
48 static inline int hw_breakpoint_len(unsigned long dr7, int index)
49 {
50     int len = ((dr7 >> (DR7_LEN_SHIFT + (index * 4))) & 3);
51     return (len == 2) ? 8 : len + 1;
52 }
53 
54 static int hw_breakpoint_insert(CPUX86State *env, int index)
55 {
56     CPUState *cs = env_cpu(env);
57     target_ulong dr7 = env->dr[7];
58     target_ulong drN = env->dr[index];
59     int err = 0;
60 
61     switch (hw_breakpoint_type(dr7, index)) {
62     case DR7_TYPE_BP_INST:
63         if (hw_breakpoint_enabled(dr7, index)) {
64             err = cpu_breakpoint_insert(cs, drN, BP_CPU,
65                                         &env->cpu_breakpoint[index]);
66         }
67         break;
68 
69     case DR7_TYPE_IO_RW:
70         /* Notice when we should enable calls to bpt_io.  */
71         return hw_breakpoint_enabled(env->dr[7], index)
72                ? HF_IOBPT_MASK : 0;
73 
74     case DR7_TYPE_DATA_WR:
75         if (hw_breakpoint_enabled(dr7, index)) {
76             err = cpu_watchpoint_insert(cs, drN,
77                                         hw_breakpoint_len(dr7, index),
78                                         BP_CPU | BP_MEM_WRITE,
79                                         &env->cpu_watchpoint[index]);
80         }
81         break;
82 
83     case DR7_TYPE_DATA_RW:
84         if (hw_breakpoint_enabled(dr7, index)) {
85             err = cpu_watchpoint_insert(cs, drN,
86                                         hw_breakpoint_len(dr7, index),
87                                         BP_CPU | BP_MEM_ACCESS,
88                                         &env->cpu_watchpoint[index]);
89         }
90         break;
91     }
92     if (err) {
93         env->cpu_breakpoint[index] = NULL;
94     }
95     return 0;
96 }
97 
98 static void hw_breakpoint_remove(CPUX86State *env, int index)
99 {
100     CPUState *cs = env_cpu(env);
101 
102     switch (hw_breakpoint_type(env->dr[7], index)) {
103     case DR7_TYPE_BP_INST:
104         if (env->cpu_breakpoint[index]) {
105             cpu_breakpoint_remove_by_ref(cs, env->cpu_breakpoint[index]);
106             env->cpu_breakpoint[index] = NULL;
107         }
108         break;
109 
110     case DR7_TYPE_DATA_WR:
111     case DR7_TYPE_DATA_RW:
112         if (env->cpu_watchpoint[index]) {
113             cpu_watchpoint_remove_by_ref(cs, env->cpu_watchpoint[index]);
114             env->cpu_watchpoint[index] = NULL;
115         }
116         break;
117 
118     case DR7_TYPE_IO_RW:
119         /* HF_IOBPT_MASK cleared elsewhere.  */
120         break;
121     }
122 }
123 
124 void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7)
125 {
126     target_ulong old_dr7 = env->dr[7];
127     int iobpt = 0;
128     int i;
129 
130     new_dr7 |= DR7_FIXED_1;
131 
132     /* If nothing is changing except the global/local enable bits,
133        then we can make the change more efficient.  */
134     if (((old_dr7 ^ new_dr7) & ~0xff) == 0) {
135         /* Fold the global and local enable bits together into the
136            global fields, then xor to show which registers have
137            changed collective enable state.  */
138         int mod = ((old_dr7 | old_dr7 * 2) ^ (new_dr7 | new_dr7 * 2)) & 0xff;
139 
140         for (i = 0; i < DR7_MAX_BP; i++) {
141             if ((mod & (2 << i * 2)) && !hw_breakpoint_enabled(new_dr7, i)) {
142                 hw_breakpoint_remove(env, i);
143             }
144         }
145         env->dr[7] = new_dr7;
146         for (i = 0; i < DR7_MAX_BP; i++) {
147             if (mod & (2 << i * 2) && hw_breakpoint_enabled(new_dr7, i)) {
148                 iobpt |= hw_breakpoint_insert(env, i);
149             } else if (hw_breakpoint_type(new_dr7, i) == DR7_TYPE_IO_RW
150                        && hw_breakpoint_enabled(new_dr7, i)) {
151                 iobpt |= HF_IOBPT_MASK;
152             }
153         }
154     } else {
155         for (i = 0; i < DR7_MAX_BP; i++) {
156             hw_breakpoint_remove(env, i);
157         }
158         env->dr[7] = new_dr7;
159         for (i = 0; i < DR7_MAX_BP; i++) {
160             iobpt |= hw_breakpoint_insert(env, i);
161         }
162     }
163 
164     env->hflags = (env->hflags & ~HF_IOBPT_MASK) | iobpt;
165 }
166 
167 bool check_hw_breakpoints(CPUX86State *env, bool force_dr6_update)
168 {
169     target_ulong dr6;
170     int reg;
171     bool hit_enabled = false;
172 
173     dr6 = env->dr[6] & ~0xf;
174     for (reg = 0; reg < DR7_MAX_BP; reg++) {
175         bool bp_match = false;
176         bool wp_match = false;
177 
178         switch (hw_breakpoint_type(env->dr[7], reg)) {
179         case DR7_TYPE_BP_INST:
180             if (env->dr[reg] == env->eip) {
181                 bp_match = true;
182             }
183             break;
184         case DR7_TYPE_DATA_WR:
185         case DR7_TYPE_DATA_RW:
186             if (env->cpu_watchpoint[reg] &&
187                 env->cpu_watchpoint[reg]->flags & BP_WATCHPOINT_HIT) {
188                 wp_match = true;
189             }
190             break;
191         case DR7_TYPE_IO_RW:
192             break;
193         }
194         if (bp_match || wp_match) {
195             dr6 |= 1 << reg;
196             if (hw_breakpoint_enabled(env->dr[7], reg)) {
197                 hit_enabled = true;
198             }
199         }
200     }
201 
202     if (hit_enabled || force_dr6_update) {
203         env->dr[6] = dr6;
204     }
205 
206     return hit_enabled;
207 }
208 
209 void breakpoint_handler(CPUState *cs)
210 {
211     X86CPU *cpu = X86_CPU(cs);
212     CPUX86State *env = &cpu->env;
213 
214     if (cs->watchpoint_hit) {
215         if (cs->watchpoint_hit->flags & BP_CPU) {
216             cs->watchpoint_hit = NULL;
217             if (check_hw_breakpoints(env, false)) {
218                 /*
219                  * FIXME: #DB should be delayed by one instruction if
220                  * INHIBIT_IRQ is set (STI cannot trigger a watchpoint).
221                  * The delayed #DB should also fuse with one generated
222                  * by ICEBP (aka INT1).
223                  */
224                 raise_exception(env, EXCP01_DB);
225             } else {
226                 cpu_loop_exit_noexc(cs);
227             }
228         }
229     } else {
230         if (cpu_breakpoint_test(cs, env->eip, BP_CPU)) {
231             check_hw_breakpoints(env, true);
232             raise_exception(env, EXCP01_DB);
233         }
234     }
235 }
236 
237 target_ulong helper_get_dr(CPUX86State *env, int reg)
238 {
239     if (reg >= 4 && reg < 6) {
240         if (env->cr[4] & CR4_DE_MASK) {
241             raise_exception_ra(env, EXCP06_ILLOP, GETPC());
242         } else {
243             reg += 2;
244         }
245     }
246 
247     if (env->dr[7] & DR7_GD) {
248         env->dr[7] &= ~DR7_GD;
249         env->dr[6] |= DR6_BD;
250         raise_exception_ra(env, EXCP01_DB, GETPC());
251     }
252 
253     return env->dr[reg];
254 }
255 
256 void helper_set_dr(CPUX86State *env, int reg, target_ulong t0)
257 {
258     if (reg >= 4 && reg < 6) {
259         if (env->cr[4] & CR4_DE_MASK) {
260             raise_exception_ra(env, EXCP06_ILLOP, GETPC());
261         } else {
262             reg += 2;
263         }
264     }
265 
266     if (env->dr[7] & DR7_GD) {
267         env->dr[7] &= ~DR7_GD;
268         env->dr[6] |= DR6_BD;
269         raise_exception_ra(env, EXCP01_DB, GETPC());
270     }
271 
272     if (reg < 4) {
273         if (hw_breakpoint_enabled(env->dr[7], reg)
274             && hw_breakpoint_type(env->dr[7], reg) != DR7_TYPE_IO_RW) {
275             hw_breakpoint_remove(env, reg);
276             env->dr[reg] = t0;
277             hw_breakpoint_insert(env, reg);
278         } else {
279             env->dr[reg] = t0;
280         }
281     } else {
282         if (t0 & DR_RESERVED_MASK) {
283             raise_exception_err_ra(env, EXCP0D_GPF, 0, GETPC());
284         }
285         if (reg == 6) {
286             env->dr[6] = t0 | DR6_FIXED_1;
287         } else {
288             cpu_x86_update_dr7(env, t0);
289         }
290     }
291 }
292 
293 /* Check if Port I/O is trapped by a breakpoint.  */
294 void helper_bpt_io(CPUX86State *env, uint32_t port,
295                    uint32_t size, target_ulong next_eip)
296 {
297     target_ulong dr7 = env->dr[7];
298     int i, hit = 0;
299 
300     for (i = 0; i < DR7_MAX_BP; ++i) {
301         if (hw_breakpoint_type(dr7, i) == DR7_TYPE_IO_RW
302             && hw_breakpoint_enabled(dr7, i)) {
303             int bpt_len = hw_breakpoint_len(dr7, i);
304             if (port + size - 1 >= env->dr[i]
305                 && port <= env->dr[i] + bpt_len - 1) {
306                 hit |= 1 << i;
307             }
308         }
309     }
310 
311     if (hit) {
312         env->dr[6] = (env->dr[6] & ~0xf) | hit;
313         env->eip = next_eip;
314         raise_exception(env, EXCP01_DB);
315     }
316 }
317